Xerographic developing apparatus



1%? KLAZUO OBUCHI 3,336,904

XEROGRAPHI C DEVELOP ING APPARATUS Filed Aug. '7, 1964 I N VEN TOR.

United States Patent 3,336,904 XEROGRAPHIC DEVELOPING APPARATUS KazuoObuchi, Kanagawa-ken, Japan, assignor to Fuji Shashin Film KabushikiKaisha, Kanagawa-ken, Japan, a corporation of Japan Filed Aug. 7, 1964,Ser. No. 388,120 Claims priority, application Japan, Aug. 13, 1963,38/42,794 4 Claims. (Cl. 118-637) ABSTRACT OF THE DISCLOSURE Axerographic developing apparatus including a hopper supplying developerto a latent image bearing material in a cascade fashion, with at leastone gas jet nozzle positioned above the material and below the hopper.The gas stream flowing from the nozzle thereby rolls the developer overthe image surface of the material and allows toner in the developer totransfer to the latent image.

- The present invention relates to a xerographic developing apparatuswherein feeding of a developer is performed by a gas flow.

It is Well known that one of the best developing process adopted in thexerography is a cascade developing process. In a limited sense of thecascade developing process, however, it is necessary to incline thesensitive surface with a certain gradient relative to the horizontalplane so that the force of gravity may cause developer to flow along thesensitive surface.

So that any developer commonly used at present may flow smoothly on thesensitive surface, an inclination thereof in an angle of more thantwenty degrees is required, the degree of the inclination depends on theshape and size of the developer as used. In other words the inclinationless than twenty degrees disturbs the free flowing of developer andconsequently satisfactory development cannot be obtained In order tocarry out the cascade developing process on a substantially horizontalplane some external force rather than the force of gravity is required.For instance, carrier in developer is made of magnetic material, thenthe magnetic force is used for flowing the developer.

The essential feature of the present invention resides in that thefeeding of developer to the sensitive material is performed by means ofthe force due to the gas or gases flow.

The present invention will be better understood in the followingdescription made with reference to the drawings, wherein:

FIG. 1 is a perspective view of the embodiment according to the presentinvention with one part thereof broken down, showing the principle ofthe present invention; and

FIG. 2 is a sectional view of the embodiment as shown in FIG. 1.

Referring to FIG. 1, 1 indicates the xerographic sensitive material,this material with the sensitive surface upsided travelling in thedirection indicated by arrow 2. A duct 3, which has an opening only atthe bottom is installed perpendicular to the travelling direction of thesensitive material 1. Narrow gaps are left between the side walls of theduct 3 and the surface of the sensitive material so that the movement ofthe sensitive material may not be disturbed. In the duct 3 there areprovided a hopper for supplying developer 4 and gas jet nozzles 5, 6 and7. Developer is supplied from the hopper 4 onto the surface of thesensitive material 1. The hopper may be shaped so as to give developerthe initial tangential velocity. Developer, in general, cannot continueflowing against friction and therefore, it stops after flowing a certaindistance. Being supplied at a constant pressure from gas supplying tubes8, 9 and 10 to gas jet nozzles 5, 6 and 7, gas flows in the directionperpendicular to the travelling direction of the sensitive material 1,thereby causing developer to continue flowing smoothly on the sensitivematerial so that satisfactory developing may be performed.

In the description of the principle of the present invention, forconvenience, it is supposed that developer flows in the directionperpendicular to the travelling direction of the sensitive material.This orientation, in case of developing long and broad sensitivematerial, is advantageous from the economical point of view.

It is not always necessary to maintain the flow of developer transverseto the travelling direction of the sensitive material. Of course, theflowing direction of developer may be selected within the range fromright angles to parallel to the travelling direction of the sensitivematerial, if required in designing.

If the developer departs from the enclosure of the duct 3, the developerwill not be influenced by the gas blown off from the nozzles 5, 6 and 7,so it can not continue to flow and is taken off with the sensitivematerial, so resulting in irregularity in development. In order toobtain regular development it is desirable that the gas flow has noirregular component therein. It is also desirable to give the gas flowthe component cancelling the component in the travelling direction ofthe sensitive material. As a method for maintaining the regularity inthe gas flow, as commonly known in the wind tunnel and the like, it issupposed that guide blades are provided within the duct and the nozzle.

As a method for cancelling the travelling component of the sensitivematerial it is supposed that the nozzles and the guide blades arearranged with a slight gradient in the opposite direction to thetravelling direction of the sensitive material.

According to the above methods, however, it is supposed that theparticles of developer collide with each other, resulting in theirregular flow of developer and the flow of developer partially departsfrom the enclosure.

of the duct 3.

Therefore, it is desirable that gas jet nozzles 12 are provided on theside walls of the duct 3. Then, the air blowing in the directionindicated by arrow 13 prevents the departure of developer from theinterior of the duct.

According to the xerographic developing process of the present inventiondeveloper can flow smoothly and in the case the gas flow which windpressure does not cause carrier and toner to separate from each other isapplied the outcome of development is similar to that obtained accordingto the so-called cascade developing process.

In the case the stronger gas flow is applied, toner will separate fromcarrier to suspend in the gas flow, resulting in the development similarto that obtained according to the so-called powder cloud developingprocess. Both of them, accordingly, fall within the scope of thepresent.

invention.

What is claimed is:

1. A xerographic developing apparatus comprising a hopper which isadapted to supply a developer consisting of a toner and a carrier to alatent image bearing material in a cascade fashion, and at least one gasjet nozzle positioned above said material and below said hopper, therebyallowing the gas stream flowing from said nozzle to roll the developerover the image surface of said material and allowing the toner totransfer to the latent image.

2. An apparatus for developing a xerographic sensitive material bearinga latent image, said apparatus comprising means to advance said materialalong a fixed path, hopper means disposed above said path and adapted tosupply a developer consisting of a toner and a carrier to said materialin a cascade fashion, and at least one gas jet nozzle positioned abovesaid path and below said hopper and adapted to emit a gas stream towardsaid material to roll the developer over the image surface of saidmaterial and to allow the toner to transfer to the latent image.

3. The apparatus of claim 2, wherein said nozzles are positioned so thatsaid gas stream flows therefrom in a direction at right angles to thedirection of advancement of said material.

4. The apparatus of claim 3, further comprising a pair of additionalnozzles disposed adjacent the ends of said hopper means above said path,one of said additional nozzles adapted to emit a gas stream towards saidmaterial in the same direction as the direction of advancement thereof,and the other of said additional nozzles adapted to emit a gas streamtowards said material in an opposite direction to the direction ofadvancement thereof.

References Cited UNITED STATES PATENTS CHARLES A. WILLMUTH, PrimaryExaminer.

PETER FELDMAN, Assistant Examiner.

1. A XEROGRAPHIC DEVELOPING APPARATUS COMPRISING A HOPPER WHICH ISADAPTED TO SUPPLY A DEVELOPER CONSISTING OF A TONER AND A CARRIER TO ALATENT IMAGE BEARING MATERIAL IN A CASCADE FASHION, AND AT LEAST ONE GASJET NOZZLE POSITIONED ABOVE SAID MATERIAL AND BELOW SAID HOPPER, THEREBYALLOWING THE GAS STREAM FLOWING FROM SAID NOZZLE TO ROLL THE DEVELOPEROVER THE IMAGE SURFACE OF SAID MATERIAL AND ALLOWING THE TONER TOTRANSFER TO THE LATENT IMAGE.